Buggy code:
public class SourceType extends Member implements IType { protected static final String [ ] fgEmptyList = new String [ ] { } ; protected SourceType ( JavaElement parent , String name ) { } public void codeComplete ( char [ ] snippet , int insertion , int position , char [ ] [ ] localVariableTypeNames , char [ ] [ ] localVariableNames , int [ ] localVariableModifiers , boolean isStatic , ICompletionRequestor requestor ) throws JavaModelException { } public void codeComplete ( char [ ] snippet , int insertion , int position , char [ ] [ ] localVariableTypeNames , char [ ] [ ] localVariableNames , int [ ] localVariableModifiers , boolean isStatic , ICompletionRequestor requestor , WorkingCopyOwner owner ) throws JavaModelException { if ( requestor == null ) { <START_BUG> Assert . isTrue ( false , "completion<seq2seq4repair_space>requestor<seq2seq4repair_space>cannot<seq2seq4repair_space>be<seq2seq4repair_space>null" ) ; <END_BUG> } JavaProject project = ( ( JavaProject ) ( getJavaProject ( ) ) ) ; SearchableEnvironment environment = ( ( SearchableEnvironment ) ( project . getSearchableNameEnvironment ( ) ) ) ; NameLookup nameLookup = project . getNameLookup ( ) ; CompletionRequestorWrapper requestorWrapper = new CompletionRequestorWrapper ( requestor , nameLookup ) ; CompletionEngine engine = new CompletionEngine ( environment , requestorWrapper , project . getOptions ( true ) , project ) ; requestorWrapper . completionEngine = engine ; String source = getCompilationUnit ( ) . getSource ( ) ; if ( ( ( source != null ) && ( insertion > ( - 1 ) ) ) && ( insertion < ( source . length ( ) ) ) ) { try { JavaModelManager manager = JavaModelManager . getJavaModelManager ( ) ; ICompilationUnit [ ] workingCopies = manager . getWorkingCopies ( owner , true ) ; nameLookup . setUnitsToLookInside ( workingCopies ) ; String encoding = project . getOption ( JavaCore . CORE_ENCODING , true ) ; char [ ] prefix = CharOperation . concat ( source . substring ( 0 , insertion ) . toCharArray ( ) , new char [ ] { '{' } ) ; char [ ] suffix = CharOperation . concat ( new char [ ] { '}' } , source . substring ( insertion ) . toCharArray ( ) ) ; char [ ] fakeSource = CharOperation . concat ( prefix , snippet , suffix ) ; BasicCompilationUnit cu = new BasicCompilationUnit ( fakeSource , null , getElementName ( ) , encoding ) ; engine . complete ( cu , ( ( prefix . length ) + position ) , prefix . length ) ; } finally { if ( nameLookup != null ) { nameLookup . setUnitsToLookInside ( null ) ; } } } else { engine . complete ( this , snippet , position , localVariableTypeNames , localVariableNames , localVariableModifiers , isStatic ) ; } } public IField createField ( String contents , IJavaElement sibling , boolean force , IProgressMonitor monitor ) throws JavaModelException { } public IInitializer createInitializer ( String contents , IJavaElement sibling , IProgressMonitor monitor ) throws JavaModelException { } public IMethod createMethod ( String contents , IJavaElement sibling , boolean force , IProgressMonitor monitor ) throws JavaModelException { } public IType createType ( String contents , IJavaElement sibling , boolean force , IProgressMonitor monitor ) throws JavaModelException { } public boolean equals ( Object o ) { } protected boolean equalsDOMNode ( IDOMNode node ) { } public IMethod [ ] findMethods ( IMethod method ) { } public IType getDeclaringType ( ) { } public int getElementType ( ) { } public IField getField ( String name ) { } public IField [ ] getFields ( ) throws JavaModelException { } public String getFullyQualifiedName ( ) { } public String getFullyQualifiedName ( char enclosingTypeSeparator ) { } public IInitializer getInitializer ( int count ) { } public IInitializer [ ] getInitializers ( ) throws JavaModelException { } public IMethod getMethod ( String name , String [ ] parameterTypeSignatures ) { } public IMethod [ ] getMethods ( ) throws JavaModelException { } public IPackageFragment getPackageFragment ( ) { } public IJavaElement getPrimaryElement ( boolean checkOwner ) { } public String getSuperclassName ( ) throws JavaModelException { } public String [ ] getSuperInterfaceNames ( ) throws JavaModelException { } public IType getType ( String name ) { } public String getTypeQualifiedName ( ) { } public String getTypeQualifiedName ( char enclosingTypeSeparator ) { } public IType [ ] getTypes ( ) throws JavaModelException { } public boolean isAnonymous ( ) throws JavaModelException { } public boolean isClass ( ) throws JavaModelException { } public boolean isInterface ( ) throws JavaModelException { } public boolean isLocal ( ) throws JavaModelException { } public boolean isMember ( ) throws JavaModelException { } public ITypeHierarchy loadTypeHierachy ( InputStream input , IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy loadTypeHierachy ( InputStream input , WorkingCopyOwner owner , IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newSupertypeHierarchy ( IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newSupertypeHierarchy ( IWorkingCopy [ ] workingCopies , IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newSupertypeHierarchy ( WorkingCopyOwner owner , IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newTypeHierarchy ( IJavaProject project , IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newTypeHierarchy ( IJavaProject project , WorkingCopyOwner owner , IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newTypeHierarchy ( IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newTypeHierarchy ( IWorkingCopy [ ] workingCopies , IProgressMonitor monitor ) throws JavaModelException { } public ITypeHierarchy newTypeHierarchy ( WorkingCopyOwner owner , IProgressMonitor monitor ) throws JavaModelException { } public String [ ] [ ] resolveType ( String typeName ) throws JavaModelException { } public String [ ] [ ] resolveType ( String typeName , WorkingCopyOwner owner ) throws JavaModelException { } protected void toStringInfo ( int tab , StringBuffer buffer , Object info ) { } }

Fix:
throw new IllegalArgumentException ( "Completion<seq2seq4repair_space>requestor<seq2seq4repair_space>cannot<seq2seq4repair_space>be<seq2seq4repair_space>null" ) ;